Answer
$\frac{x^2}{4}+(y-1)^2=1$
Work Step by Step
The ellipse has a major axis parallel to the x-axis, hence the equation of the ellipse here has the form $\frac{(x-h)^2}{a^2}+\frac{(y-k)^2}{b^2}=1$, where $a\gt b\gt0$ and $(h,k)$ is the center.
$(h,k)=(0,1)$, $a=2$, $b=1$, hence the equation is: $\frac{(x-0)^2}{2^2}+\frac{(y-1)^2}{1^2}=1\\\frac{x^2}{4}+(y-1)^2=1$
